The purpose of this project is to describe the molecular events regulating the differentiation of embryonic chick lens cells as a model for understanding the control of embryonic cellular differentiation. Within this past fiscal year, we have 1) quantitated delta-crystallin mRNA during lens cell differentiation, and correlated delta-crystallin gene expression with lens cell elongation; 2) established that the delta-crystallin genes are not amplified during lens cell differentiation; 3) demonstrated that the synthesis of delta-, alpha-, beta- and non-crystallin polypeptides are noncoordinately regulated during lens cell differentiation; 4) made considerable progress on our understanding of the subunit composition and the structure of embryonic delta-crystallin; and 5) initiated experiments directed towards investigations of tubulin synthesis and gene expression during lens cell differentiation.